#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 3e5;
const ll INF = 1e18;
ll a[MAXN], b[MAXN];
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int n, days; cin >> n >> days;
for (int i=0; i<n; i++) cin >> a[i];
for (int i=0; i<n; i++) cin >> b[i];
if (days == 1) {
int B = 0;
for (int i=0; i<n; i++) B += b[i] >= a[i];
if (B >= 2) {
ll ans = INF;
for (int i=0; i<n; i++) {
ans = min(ans, max(a[i], b[i]));
}
cout << ans << '\n';
} else {
ll ans = INF, mxB = 0; int check = -1;
for (int i=0; i<n; i++) {
if (b[i] > a[i]) {
check = i;
continue;
}
ans = min(ans, a[i]);
mxB = max(mxB, b[i]);
}
if (check == -1 or a[check] >= ans) cout << ans << '\n';
else cout << max(a[check], min({b[check], ans, mxB})) << '\n';
}
} else {
// ll l = 0, r = 1000000000LL * days; ll ans = 0;
// while (l <= r) {
// ll mid = (l + r) / 2;
// ll available = 0, needed = 0;
// for (int i=0; i<n; i++) {
// if (days * a[i] mid)
// }
// if (available >= needed) {
// ans = mid;
// l = mid+1;
// } else r = mid-1;
// }
// cout << ans << '\n';
}
return 0;
}
